Two-stroke internal-combustion engine



March 15,1949. 0. PETERSEN TWO-STROKE INTERNAL-COMBUSTION ENGINE 2 Sheets-Sheet 1 Filed Jan. 25, 1946.

2 H 7 0 H H F x I II I, I I 1 l I m 9 6 Izbv cantor O. Petersen March 15, 1949. o. PETERSEN 2,464,652

TWO- STROKE LNTERNAL- COMBUSTION ENGINE Filed Jan 25, 1946 2 Sheets-Sheet 2 .122, v' ezvtoz human. s, me

Ove Petersen, (ientofte, Denmark Application January 28, 1946, Serial No. 043,281

In Denmark Ill! 18, 1942 Section 1, rasue u no. August s, 1948 Patent expires July 18, 1962 l- Claims. Internal combustion engines are known which the cylinder liner is bolted to the cylinder cover and hangs within a cylinder frame or other frame part supporting the latter, which. frame part is in turn connected with the other part of the frame by long stay bolts secured to the bed plate. The cylinder frame or corresponding frame part surrounding the cylinder entails in this construction an undesired increase in the weight and cost of production of the engine, and the fact that the cylinder lies hidden entails that its accessibility for the daily inspection and upkeep of especially the connecting parts for cooling medium, lubricating oil. .etc. leaves a lot to be desired. Furthermore the bolts with which cylinder cover is secured to the rigid frame parts must be placed comparatively far from the pyliii der, which is not expedient, amongst other thing's I out of regard to the bending tensions acting the cover. Finally most of the cylinder fittings, such as fuel valve, starting valve, safety valve, indicator valve, etc. must be placed in the cover.

It is also known to provide the cylinder withan outward-projecting flange fitted at the bo ttom, by means of which it is bolted direct on top of the frame, the cylinder cover then being bolted direct to the upper end of the cylinder. In this construction the whole of the combustion pressure is to be transferred from the cover to the frame through the cylinder liner proper. which must therefore be made inordinately thick.

Furthermore engines are known in which the cylinder liner bears with a shoulder on a heavy horizontal plate placed on top of the frame and is closed at the top with a cover in the form of a separately fitted plate secured by a close ring of bolts, which are screwed into the said horizontal plate and tighten on a plate fitted over'the cover. 1

In this construction both the exhaust ports and the scavenge ports are placedbelow in the cylin der, and the whole is surrounded by a cooling jacket, the water space of which is through bores for the bolts in the ribs situated between-the ports put in communication with'eooling spaces-in the said horizontal plate. The whole is complicated and irrational, especially on necount of the unusually many places in which-it is necessary to procure sealing for the cooling;

water. and on account of the fact it is necessary to make the ports omparatively narrow in order that the cooling water. channels and the clamping bolts may get Zoom to pass through the intermediary ribs.

This invention relates to-a two-stroke internal" combustion engine, in which the said drawbacks have been remedied. The engine in accordance with the invention has longitudinal scavenging through an exhaust valve fitted above in the cylinder and is of the kind. in which the cylinder liner 5 and the cylinder cover are secured to the rigid parts of the frame of the engine by means of stay boltssecured to the frame, which stay bolts Bitten on the cover and keep a shoulder on the cylinder liner pressed against a bearing surface on the rigid frame parts. The characteristic feature of engines in accordance with the invention consists first and foremost in the fact that the said shoulder is situated in the immediate vicinity of scavenging ports fitted below in the l cylinder, and below the cooling jacket of the cylinder, around which and as close as possible to which the stay bolts are fitted in a number of four per cylinder.

, By this arrangement a remarkably clear and perspicuous engine construction is attained, where the total weight of the cylinder aggregate has been brought down to the least possible while at the same time the possibility has been created 7 of a rational shaping of cylinder as well as cover.

The cylinder proper lies quite free on the part to be provided with cooling arrangements, and the sealing of its cooling jackets and the various connecting parts is therefore very easily surveyed.

. Most of the fittings, fuel valve, starting valve, etc.

so may be placed in the cylinder liner instead of in the cover, whereby it becomes possible to.give the cover a very simple construction, which in part is cheap to manufacture, in part very resistible to heat tensions and the mechanical stresses occurring during the working. Likewise there will be room for making the exhaust valve 7 placed in the cover as large as the newest investigations into the exhaust process show that it ought to be, and in the construction of the exhaust channel in the cover one is likewise not bound by the regard to the arrangement of the remaining cylinder fittings.

The new construction gives also the possibility on. very simple and quick partial disconnection g orthe engine, the cover as well as the cylinder liner getting loose and ableto be removed, when the nuts of the four stay bolts are taken oil.

The engine in accordance with the invention may be made in two different variants, as the so shoulder, with which the cylinder bears against the rigid frame parts, may be situated either above the scavenge ports or below the latter.

" The former variant is best suited for smaller engines, 1. e. trunk engines with cylinder diamss eters of up to about 350 mm., while the other embodiment is more advantageous in engines with larger cylinder units and especially in larger engines with crossheads.

The rigid frame parts, against which the shoulder of the cylinder bears, will generally consist of a girder running in the longitudinal direction of the engines, which girder is supported from the bedplate in the usual manner by means of light frames fitted between the cylinder units. In the embodiments where the shoulder of the cylinder is situated higher than the scavenge ports, these will thus be situated freely within the hollow girder, which is then a way known per se used as scavenge air box. In the other embodiments, where the scavenge ports are situated higher than the shoulder of the cylinder, there is in accord ance with the invention on the top of the girder fitted a scavenge air box surrounding the scavenge ports. The stay bolts must be of so high a tension that they can keep the whole of the construction securely clamped against thecombustion pressure and ensure a sealing between the cover and the cylinder, and furthermore they must be able to take up the heat tensions arising by the heat expansion of the clamped part of the cylinder. In order to keep the extra tensions arising hereby within moderate limits it may, especially in larger engines where the stay bolts are already strongly loaded, be advantageous to insert resilient elements in the connection between the stay bolts and the cover or the rigid frame parts, e. g. the so-called Belleville springs, which consist of dished washers fitted under the nuts and alternately facing opposite ways.

The features necessary for understanding the invention will appear from the following speci- 4 a protruding part 8.'which is carried some distance down into the upper end 01' the cylinder.

The various fittings, such as fuel valve, starting valve, etc. are inserted in suitable borings in the upper end ot the cylinder-liner. Such a boring has by 'way of an example been indicated by 40 in Fig. 3.

-- -The whole construction is held together by four stay bolts 9, which are fitted around the cylinder .asclose as possible to the cooling jacket of the latter and secured in a suitable way to the rigid engine parts (the girder I). The upper ends of the stay bolts pass, in the usual way through holes in the cover '6 and clamps the latter by means of nuts I0.

- I-n' the embodiment shown in Fig. 1 the shoulder 4 'is' situated above the usual scavenge ports I! of I of the cylinder is placed below the scavenge ports fication in connection with the drawing, which shows two different embodiments.

Fig. 1 shows one embodiment in section through part of the engine cylinder with cover and adjacent frame parts on line A--A in Fig. 2,

Fig. 2 what has been shown in Fig. I seen from above,

Fig. 3 the other embodiment in a vertical longitudinal section transverse to the crank shaft,

Fig. 4 the embodiment shown in Fig. 3 seen from above, and

Fig. 5 a section on line VV in Fig. 4. 0n the drawing, which is in part schematical,

amongst other things by the omission of particulai's irrelevant to the invention, I designates in both embodiments parts of the rigid frame of the engine, which parts box-shaped girder running in the longitudinal direction of the engine. This girder may be continued through the whole length of the engine, contingently composed of shorter sections, or it may be divided into several mutually independent sections, each corresponding to one or a number of cylinder units. The cylinder shown consists of a cylinder liner 2 and a cooling jacket 3, which as shown may be cast in one piece. The cooling jacket may also, especially in larger engines, in a way known per se, be fitted separately. Below the part of the cylinder provided with cooling jacket is a ring-shaped shoulder 4, which bears against a corresponding bearing surface on the top of the girder I, the lower part of the cylinder being carried down through and centred in a hole in the upper side of the girder.

The upper end of the cylinder has been turned so as to form a ring-shaped bearing surface 5, against which a corresponding bearing surface on the cylinder cover 6 bears. The cover has been centred in relation to the cylinder by means of are here made as a the. cylinder, so that these lie freely within the interior I2 of the hollow girder I. The girder can therefore be used as a scavenge air box in a way'known 'per se. In the cylinder cover in this embodiment, which is especially suited for smaller engines, there are the seat and guide for an exhaust valve, not shown; and an exhaust channel I; The cover is in the usual way provided with a cooling space, one cooling medium pipe of which is shown by Hi.

In this embodiment the stay bolts are screwed .d'own into tapped hol'es II in the upper side of the g irder I.

I3. The hollow'girder I isby means of a dia- 'phragin 21 with a stuffing box 28 for the piston rod divided into two compartments, into the upper of which the lower end of the cylinder Opens out freely. On the top of the girder I is a light scavenge air box I5 surrounding the scavenge ports, with which box the upper compartment of the girder communicates through a chan-- nel 32 for the elimination of the pumping action occurring in the'girder by the motion of the piston down below the scavenge 'ports. The scavenge air box is sealed against the cylinder liner by means of a stuffing box 39 and is supplied with scavenge air from a scavenge air pump made up of the cylindrical crosshead 22, which works in a cylindrical crosshead guide 23 opening out into the lower compartment of the hollow girder I. This compartment of the hollow girder thus rnakes up the clearance of the scavenge air pump,

the suction and pressure 'valves of which are designated by 30 and 3!.

is centered by means of a neck 26, and it rests on light frames I6, which are arranged on the bedplate I9 of the engine between the cylinder units. The girder is secured to' the bedplate by means of stay holts 35, which are carried through the hollow verticals ll of the frames and provided with nuts I8 below the traverses of the bedplate and nuts 36 on the upper side of the girder I. The crank shaft is designated by 20, and the connectingrodbyZI.

A channel 29 leads from the scavenge 'air pump 'to the valve casing of the cured in nuts 31 on the lower side of the latter, as appears from Fig. 5. The material of the airder is therefore practically speaking only exposed to pressure tensions. The stay bolts 9 are carried air-tight through the scavenge air box l by means of stufllng boxes 38, and for the reduction of the extra tensions arising from the heat expansions of the cylinder they are provided with a spring arrangement in the form of a pair of oppositely facing dished washers 34, a so-called Belleville spring, under the cover nut l0.

As shown in Figs. 3 and 4 there is here a separate casing 33 with exhaust channel 1 for the exhaust valve.

The invention is not bound to the constructions shown and described, the particulars of which, especially as to the kind and shaping of the rigid engine parts, on which the cylinder rests, may be altered in various ways, when only care is taken that the stay bolts are placed as close to the cylinder as possible, and that the whole part of the cylinder provided with cooling arrangements is situated above the rigid frame.

I claim:

1. In two-stroke internal combustion engine, a cylinder cover with an exhaust valve, a cylinder liner having scavenging air ports at the lower end, a cooling jacket for the cylinder liner extending from the upper cylinder end downwards to a short distance above the scavenging ports, a stationary frame member forming a longitudinal girder of the engine and having a seating surface on the upper portion thereof, four stay bolts substantially equally spaced around the cylinder immediately outside the cooling jacket thereof, and anchored with their lower ends in said frame member so as to tighten upon the upper side of the cover and force the latter into sealing engagement with the upper end of the cylinder liner, a laterally projecting shoulder on the cylinder liner situated immediately adjacent the scavenging air ports and seated upon said seating surface.

2. In a two-stroke internal combustion en ine; a cylinder cover with an exhaust valve, 9. cylinder liner having scavenging air ports at the lower end, a cooling jacket for the cylinder liner extending from the upper cylinder end downwards to a short distance above the scavenging ports, a staa cylinder cover with an exhaust valve, a cylinder liner having scavenging air ports at the lower end, a cooling jacket for the cylinder liner extending from the upper cylinder end downwards to a short distance above the scavenging ports, a stationary frame member forming a longitudinal girder of the engine and having a seating surface on the upper portion thereof, four stay bolts substantially equally spaced around the cylinder immediately outside the cooling jacket thereof, and anchored with their lower ends in said frame member so as to tighten upon the upper side ofthe cover and force the latter into sealing engagement with the upper end of the cylinder liner,

tionary frame member forming a longitudinal girder of the engine and having a seating surface on the upper portion thereof, four stay bolts substantially equally spaced around the cylinder a laterally projecting shoulder on the cylinder liner situated immediately below the scavenging air ports and seated upon said seating surface, and a scavenging air case enclosing the scavenging air ports mounted on the upper part of said frame.

4. Atwo-stroke internal combustion engine as claimed in claim 1 provided with resilient means interposed between the stay bolts and the cylinder cover.

5. A two-stroke internal combustion engine as claimed in claim 1 provided with resilient means interposed between the stay bolts and the frame member.

OVE PETERSEN.

REFERENCES CITED The following references are of record in the L ille of this patent:

UNITED STATES PATENTS Number Name Y Data 1,751,653 Nibbs Mar. 25, 1930 1,795,088 Jorgensen Mar. 3, 1931 2,020,461 Dennison et al. Nov. 12, 1935 2,254,410 Andresen Sept. 2, 1941 FOREIGN PATENTS Number Country Date 50.666 Netherlands 194i 

